Convert to typescript = 80% completed

[j-d-carmichael]

https://github.com/johndcarmichael/postmatex/tree/feature/to-typescript

Need to fix the tests but other than that should be a good.

[HyperCharlie]

Just wanted to say yay to this, wish I had the bandwidth to assist, just started using this library and seems like a good one.

[jflebeau]

Are you still working on this fork?

[j-d-carmichael]

I'm using this fork in a production applicaiton, but don't have the time right now to see the typescript conversion through to the end... would love a helping hand if you had time?

[mgm5198]

What needs to be updated/changed?

[j-d-carmichael]

I honestly, cannot remember :)

We are still using the JS version at the moment as it works ok... TS is at this point a nice to have